Field of the Invention
The present invention relates to a radiation imaging apparatus and a radiation imaging system.
Description of the Related Art
As a radiation imaging apparatus used for medical image diagnosis and non-destructive inspection by using radiation such as an X-ray, a radiation imaging apparatus including a matrix substrate having a pixel array obtained by combining switches including thin film transistors (TFTs) and conversion elements including photoelectric conversion elements has been put into practical use.
In recent years, multi-functionalization of the radiation imaging apparatus has been studied. As one type of the multi-functionalization, it has been studied that the radiation imaging apparatus has a built-in function of monitoring radiation irradiation. This function enables detection of a timing at which radiation irradiation from a radiation source has been started, detection of a timing at which radiation irradiation is to be stopped, and detection of an irradiation amount or an integrated irradiation amount of radiation, for example.
Japanese Patent Application Laid-Open No. 2012-15913 discusses a radiation imaging apparatus including imaging pixels for acquiring a radiation image and detection pixels for detecting radiation, and further discusses a configuration in which a signal for detecting radiation is read out via a switching element connected to the each detection pixel. To switch a conductive state of the switching element when a signal is read out of the detection pixel, a driving voltage is switched between a conductive voltage and a non-conductive voltage, as needed, to switch a conductive state of the switching element.
However, in the radiation imaging apparatus discussed in Japanese Patent Application Laid-Open No. 2012-15913, when the driving voltage is switched, a signal to be transmitted to a signal line may vary due to a parasitic element (parasitic capacitance) between a control line connected to the switching element and a signal line as a voltage on the control line changes. Therefore, the detection accuracy of radiation irradiation may be low depending on a potential variation on the signal line.